1. Field of the Invention
The present invention relates to an apparatus for determining an optimal transmission gear speed for an automotive vehicle having an automatic transmission and related methods therefor.
2. Discussion of Related Art
In an electronically controllable automatic transmission one of the functions provided by its Transmission Control Unit ("TCU") includes selecting a proper transmission gear speed in reference to a two-dimensional plane, which is made of the extent of opening of the throttle valve (i.e., represents the load to the engine) and the speed of the vehicle. More specifically, in controlling the operation of the automatic transmission, the TCU sets a transmission shift pattern in reference to the extent of opening of the throttle valve and the speed of the vehicle, and stores data representing the pattern therein. Then, the TCU selects a target transmission shift speed for the vehicle in accordance with transmission shift pattern, and generates a command signal to effect the actual shifting to the target speed in the transmission, through controlling of various valves therein.
However, since a conventional transmission shift pattern is set in reference to the driving state of the vehicle based on the above two-dimensional plane, variations in the driving state due to other factors, such as the driver intending to accelerate or decelerate the vehicle while driving on a slope or steered road, or problems resulting from abrasions of the engine or transmission gear box, etc., cannot be compensated for.